The apparatus is intended to be usable on a stand foot or on a stand column such as a stand arm, but also on other stands such as ceiling or wall mounts.
Retention of an optical viewing device by means of a stand having a stand arm is necessary in a wide variety of applications, especially in the field of medical technology. These stand arms are often embodied as one-armed carriers which are held in position by means of spring mechanisms and/or lockable brakes, and/or are motor-driven.
WO 99/01693-A presents a stand that is marketed by the Applicant as MS 1. Like previous models as well, it has a carrier arm, constructed as a parallelogram, whose geometrical extension is defined by an obliquely arranged support spring, the support spring serving as weight compensation for the load of the viewing device. In this known assemblage, the spring force is adjustable so that different weights of different or differently equipped viewing devices can be supported or compensated for.
EP 866 260 A discloses a toothed-belt-supported support element that transfers the forces for weight compensation (balance) by means of its geometrical arrangement.
In conventional assemblages, diagonal struts are thus used essentially in order to support specifically arranged carrier arms or carrier arm parts in a desired position, and to direct the stress on those assemblages obliquely into the stand columns. In some circumstances, this task could also be achieved, in the context of these assemblages for performing support functions, if no parallelogram at all were present, but rather the entire assemblage were boom-shaped.
Conventional diagonal struts often also have:    An integrated spring force of a gas spring, as already mentioned above, to compensate for (the weight of) the load.    One or more damping elements, for example gas springs or special rubber bumpers having defined spring and damping characteristics (vibration damping).    Liquid dampers.
The inventor has recognized that the known systems are disadvantageous in the following ways:    a) Insufficient stability in the vertical direction of the microscope (parallel to the optical axis), and thus low positioning accuracy. As a result of poorly controllable vibration stability, unsharp or unstable images can occur with a slow-reacting autofocus system.    b) Heavy construction, in order to achieve improve stability and low-vibration characteristics.    c) Large retention forces are necessary. The elements are thus of solid construction, thereby also (because of the increased weight) resulting in sluggishness and insufficient mobility.